King Sri Indraditya (Thai: พ่อขุนศรีอินทราทิตย์; rtgs: Pho Khun Si Inthrathit; ? – 1270) ruled the Sukhothai Kingdom from the year 1238 to circa 1270. He is credited as the founder of the Phra Ruang Dynasty, itself credited as the first historical Siamese dynasty, having a double claim to this title: for being cradled precisely in the region designated by foreigners as "Siam" (Khmer: Syāiņ; Chinese: Sien, etc.), and for being the dynasty which freed the Thai principalities from the Cambodian yoke.

https://en.wikipedia.org/wiki/Sri_Indraditya